Slide-controlled hydraulic shock absorber



Sept 19, 1939.

R. BINDER EI' AL SLIDE-CONTROLLED HYDRAULIC SHOCK ABSORBER Filed May 12, 193'! 2 Sheefs-Shqet 1 Fig 2.

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Patented Sept; 19, 1939 UNITED STATES PATENT OFFICE SLIDE-CONTROLLED HYDRAULIG SHOCK ABSORBER Richard Binder and Hermann Klein, Schweinfurt,

' Germany 6 Claims. (Cl. 188-88) This invention relates to double-acting hydraulic shock absorbers of substantially tubular construction, comprising a pump and means for conveying and controlling the working fluid therein. This shock absorber is particularly designed to damp the oscillations of spring-supported parts of vehicles, such as automobiles.

The object of the invention is to obtain a calm or soft checking of the rocking movement at the 10 end of every stroke of the piston and thus to damp the oscillations of a spring-supported body or member of a vehicle. a

This object is attained by the arrangement of a plurality of perforations or ports distributed l5 lengthwise in the wall of the pump cylinder which ports interconnect the interior of the pump with a by-pass or return passage conveying the working liquid back tothe opposite end of the pump. It is a substantial feature that the pis- 20 ton of the pump covers and uncovers the said ports during its stroke and particularly near the end thereof so that the damping effect may be regulated as desired.

Other features will appear from the sequent description and be claimed in the closing claims.

In the accompanying drawings, which form a part of this specification, three embodiments of the invention are illustrated by way of example. In the drawings- 30 Fig. 1.is a vertical sectionalview of a shock absorber according to the invention,

Figs. 2 and 3 are similar but modified constructions of the shock absorber.

Like numerals designate like or similar parts throughout all figures of the drawings.

As shown in Fig. 1-, the pump cylinder I is surrounded by the cylindrical wall I2 of a bypass or return chamber 25 in turn disposed within the cylindrical wall H of a receiver or com- 40 pensating chamber 21. The said return chamber is adapted to afford the communication between the top and bottom ends of said pump-cylinder l0 as stated hereinafter. In a foot piece 28 interconnecting the lower ends of the tubular walls I0,

45 I2 and i4 is located a check or valve i6 between the pump and the compensating chamber 21. A perforation lBa made in the body or disc i6 allows of the passage of a given amount of working liquid from the pump to the compensating to chamber 2? under pressure when the valve is closed.

Lengthwise distributed in the wall of the pump cylinder l0 there is a plurality of perforations or ports H of any shape and arranged on a spe- 55 cial disposition. Through these holes or ports H the damping liquid passes from the pump into the return chamber 25 which is connected with the lower end of the pump through a few larger ports 3|.

The upper ends of the tubes l0, l2 and H are connected and closed by a head piece 29 in which the rod IQ of a piston I8 is guided when moving upwards and downwards. A non-return valve I1 and axial channels 20 provided in the piston l8 only allow the passage therethrough when the piston moves downwards.

Suppose the pump cylinder l0 and the return chamber 25 to be entirely filled with the working liquid, such as oil, while the receiver or compensating chamber 21 requires to be only partially filled, the operation of shock absorber is as follows.

As the piston I8 is moved in the upward direction, beginning from the position shown in Fig. 1 in which all perforations II are uncovered while the non-return valve I! stands closed, the liquid filling the pump space above the piston I8 will be forced through the perforations ll into the return conduit 25; from there it will pass through ports 3| into the space below the pis- 26 ton. However, since the volume of the upper -pump space, owing to the piston rod I9 being therein enclosed, is smaller than that of the lower space, a certain amount of liquid will be drawn out of the compensating chamber 21 80 through the valve l6 into the lower pump space. In its further upward movement the piston will gradually act as a slide valve and cover the perforations ll thereby reducing the total sectional area of passage afforded by the perforations H 85 to such an amount that the increased damping effect results in a soft stopping of the oscillating movement without shock. The combined areas of the perforations II in successive longitudinal sections of the cylinder Ill from substantially the middle to the .upper end thereof increase progressively, so that the rate of acceleration in the retardation of the piston I8 is lower than it would be if the combined areas of these perforations were equal for successive sections of the upper half of said cylinder.

By the subsequent downward movement of the piston and piston rod the perforations II are uncovered, while the admission of the liquid into the upper space will take place through the piston, the valve l'l mounted therein being l'fted by the liquid pressure exerted to its lower face., The excess of liquid will not be received in the upper pump space, but refunded to the compensating chamber 21 through the small openingtlilia of the valve I6, thereby also damping the downward displacement of the piston.

The modification of the shock absorber shown in Fig.2 is completed by a safety valve I! pressed upon its seat by a strong spring lib actuated through an adjustable support lSa. This resillent valve is provided to release the device from undue pressures generated in the liquid by extraordinarily heavy shocks and is disposed at the upper end of the pump cylinder, Ill so that it operates in parallel with the control efiected by the perforations H.

In Fig. 3 a shock absorber having a similar safety valve l5 disposed in the lower end of the by-pass 25 is illustrated. Said valve is held in its closed position by a spring lib the pressure of which can be regulated through an adjustable screw ISa and it operates in series with the perforations II to release the device from undue pressures generated into liquid by heavy shocks.

In the constructions of Figs. 1, 2 and 3, the pump cylinder has a plurality of perforations longitudinally arranged in spaced relationship, and so distributed as to normally provide a substantially constant rate of retardation of the piston ll in its upward movement in the lower half of said pump cylinder, and a progressively increased rate of retardation in its upward movement in the upper' half of said pump cylinder.

For that purpose, all or at least most of the perforations are arranged from approximately the middle of the pump cylinder to the upper end thereof through which the piston rod extends. In the 'lower half of the pump cylinder, the perforations are either small in number as compared with those provided in the upper half of the cylinder as shown in the constructions of Figs. 1 and 3, in which one or two apertures are provided in said lower half, or said perforations are entirely absent from said lower half as in the construction of Fig. 2.

We claim:

l. A liquid operated double acting shock absorber comprising a pump cylinder, a piston reciprocable therein, a rod connected to said piston and extending through one end of said cylinder, said piston having a non-return valved passage therein, a cylindrical return chamber concentrically enclosing said pump cylinder and communicating at its ends with approximately opposite ends of said pump cylinder respectively, a compensating chamber concentrically'enclosing said return chamber, and a valve located near the other end of said pump cylinder between said pump cylinder and compensating chamber, and automatically moved into open position only by the movement of said piston away from said valve, said pump cylinder having a plurality of perforations longitudinally arranged in space relationship and so distributed as to normally provide a substantially constant rate of retardation of the piston in its upward movement in the lower half of said pump cylinder, and a progressively increased rate of retardation in its upward movement in the upper half of said pump cylinder, the combined areas of said perforations in successive longitudinal sections of said cylinder in its upper half increasing progressively to the upper end of said pump cylinder.

2. A liquid operated double acting shock absorber comprising a pump cylinder, a piston reciprocable therein, a rod connected to said piston and extending through one end of' said cylinder, said piston having a non-return valved passage therein, a cylindrical return chamber concentrically enclosing said cylinder and communicating at its ends with approximately opposite ends of said pump cylinder respectively, a compensating chamber concentrically enclosin said return chamber, and a disc valve located near the other end of said pump cylinder be-- tween said pump cylinder and said compensating chamber and automatically moved into open position only by the movement of said piston away from said valve, said valve 'iaving a bypass permitting recharging of the compensating chamber during the movement of said piston towards said valve, said pump cylinder having a plurality of perforations longitudinally arranged in space relationship and so distributed as to normally provide a substantially constant rate of retardation of the piston in its upward movement in the lower half of said pump cylinder, and a progressively increased rate of retardation in its upward movement in the upper half of said pump cylinder, the combined areas of said perforations in successive longitudinal sections of said cylinder in its upper half increasing progressively to the upper end of said pump cylinder.

3. A liquid operated double acting shock absorber comprising a pump cylinder, a piston re-' ciprocable therein, a rod connected to said piston and extending through one end of said cylinder, said piston having a non-return valved passage therein, a cylindrical return chamber concentrically enclosing said cylinder and communicating at its ends with approximately opposite ends of said pump cylinder respectively, a compensating chamber concentrically enclosing said return chamber, a valve located near the other end of said pump cylinder, between said pump cylinder and said compensating chamber, and automatically moved into open position only by the movement of said piston away from said valve, said pump cylinder having a plurality of perforations longitudinally arranged in space relationship and so distributed as to normally provide a substantially constant rate of retardation of the piston in its upward movement in the lower half of said pump cylinder, and a progressively increased rate of retardation in its upward-movement in the upper half of said pump cylinder, the combined areas of said perforations in successive longitudinal sections of said cylinder in its upper half increasing progressively to the upper end of said pump cylinder, and a safety valve for releasing the absorber from undue pressures generated in the liquid by heavy shocks.

4. A liquid operated double acting shock absorber comprising a pump cylinder, a piston reciprocable therein, a rod connected to said piston and extending through one end of said cylinder, said piston having a non-return valved passage therein, a cylindrical return chamber concentrically enclosing said cylinder and communieating at its ends with approximately opposite ends of said pump cylinder respectively, a compensating chamber concentrically enclosing said return chamber, and a valve located near the other end of said pump cylinder, between said pump cylinder and said compensating chamber and automatically moved into open position only by the movement of said piston away from said valve, said pump cylinder having a plurality of perforations longitudinally arranged in space relationship and so distributed as to normally provide a substantially constant rate of retardation of the piston in its upward movement in the lower half of said pump cylinder, and a progressively increased rate of retardation in its upward movement in the upper hall 01 said pump cylinder, the combined areas or said perforations in successive longitudinal sections of said cylinder in its upper half increasing progressively to the upper end oi. said pump cylinder, a nonretum spring pressed safety valve torelease' the absorber from undue pressures generated in the liquid by heavy shocks, and means for selectively and automatically moved into open position only a by the movement of said piston away from said valve, said pump cylinder having a-piurality of perforations longitudinally relationship and so distributed as to normally provide a substantially constant rate of retardation of the piston in its upward movement in the lower half oi. said pump cylinder, and a progressively increased rate of retardation in its upthe upper half of said pump cylinder, the combined areas 01 said perforations sections of said cylincreasing' progressively to the upper end or saidpmnp'cylindeaand a atone end ofithe pump cylinderyand operable in parallel with the 40 control elected by to release trically enclosing said cylinder longitudinally stantially constant rate of .piston in its upward movement in thelower half and a progressively increased rate of retardation in its upward move- I member for adjusting the tension of said spring.

6. A liquid operated double acting shock absorber comprising a pump cylinder, a piston reciprocabie therein, a rod connected to said piston and extending through one end of said cylinder,

said piston having a non-return valved passage therein, a cylindrical return chamber concenand communicat ing at its ends with approximately opposite ends of said pump cylinder respective ,a compensating chamber concentrically enclosing said return chamber, a valve located near the other end of said pump cylinder between and said compensating chamber and automatically moved into open position only by the move from said valve, said pump cylinder having a plurality of perforations arranged in space relationship and so distributed as tonormally provide a subretardation of the of said pump cylinder.

ment in the upper half oi said pump cylinder, the combined areas 01' said perforations in successive longitudinal sections of said cylinder in its upper half increasing progressively to the upper 'end of said pump cylinder, and a nonreturn said pump cylinder 

